Among the various devices for displaying video and graphics images are plasma display devices, cathode ray tube (CRT) devices, and liquid crystal display (LCD) devices. These display devices may receive digital display data from data display processing devices which may include digital video disc (DVD) players and recorders, digital tape players and recorders, satellite signal receivers, computers, digital cable television receivers, high definition television receivers, etc.
Some of the aforementioned display devices, for example plasma displays and CRT displays, include phosphor elements that may age over time as the phosphor elements are excited. A current trend among media providers, including television broadcasters, is to place static image elements within video streams. For example, during sporting events it is common for information such as team names and scores to be displayed at the upper or lower border of the image. Another example is television network logos that are commonly placed in a corner of an image. These elements remain relatively static compared to the rest of the image which is generally in motion.
Another trend is for black or grey bars to be placed either at the top and bottom edges of the display or at each side of an image. For example, when viewing a letterboxed movie on a television with a standard 4:3 aspect ratio, black bars appear at the top and bottom of the screen. Similarly, when view 4:3 content on a 16:9 widescreen display, black or grey bars appear at each side of the screen.
In the case of static display elements, a problem may occur where the pixel elements that are included within the region of the static display elements are excited to a greater degree over time the rest of the pixels of a display device. This may result in the static display region pixels aging quicker than the rest of the display pixels. In the case of the black bar regions, the display area outside of the black bar regions may age quicker than the black bar regions. This process may be referred to as pixel “burn-in.” The burn-in process may occur slowly over time or more quickly depending on the intensity of the relevant pixel values.
Over time, the effects of the varying degeneration rates of the various pixel elements may become visible, with parts of a display brighter, more vibrant, and with more accurate color representation than other parts of the display. It would be desirable to provide a solution that would help display devices to age more uniformly and to help guard against excessive burn-in.